An RFID reader is also known as an interrogator.
The main objective of an RFID reader is to transmit and recieve signals , transforming radio waves from tags into a format that computers can read.
RFID readers can provide energy to passive RFID tags. Readers can be autonomous units connected to antennas, portable units with integrated antennas, in miniature plates mounted inside printers, or integrated in big devices.
The reader is necessary to transmit energy to the tag, to receive data corresponding to communications from the tag, and to separate these kinds of signal.
Most readers are able to read and write a tag. The reading function reads data stored in the tag´s chip. In the same way, the writing function writes the corresponding data on the tag´s chip. For example, if a manufacturer sends finished products to a distribution center, they can write the manufacturer´s identification in the tag.
Reader-tag communication can use any of the four frequency bands: low, high, ultrahigh, and microwave.
Another function from the interrogator is to handle the situation if more than one tag responds automatically to its interrogatory. . This is called anti-crash prosecution and it is developed through the interrogator´s electronics using its software. A reader has to be connected through antenna cables in order to carry out the transmission and reception of signals. Portable readers can have built-in antennas or can connect to external reading modules. Readers use standard communication protocols in order to communicate.